libringbuffer/shm.h

   1 #ifndef _LIBRINGBUFFER_SHM_H
   2 #define _LIBRINGBUFFER_SHM_H
   3
   4 /*
   5  * libringbuffer/shm.h
   6  *
   7  * Copyright 2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  *
   9  * Dual LGPL v2.1/GPL v2 license.
  10  */
  11
  12 #include <stdint.h>
  13 #include <ust/usterr-signal-safe.h>
  14 #include "ust/core.h"
  15 #include "shm_types.h"
  16
  17 /*
  18  * Pointer dereferencing. We don't trust the shm_ref, so we validate
  19  * both the index and offset with known boundaries.
  20  */
  21 static inline
  22 char *_shmp(struct shm_object_table *table, struct shm_ref *ref)
  23 {
  24         struct shm_object *obj;
  25         size_t index, offset;
  26
  27         index = (size_t) ref->index;
  28         if (unlikely(index >= table->allocated_len))
  29                 return NULL;
  30         obj = &table->objects[index];
  31         offset = (size_t) ref->offset;
  32         if (unlikely(offset >= obj->memory_map_size))
  33                 return NULL;
  34         return &obj->memory_map[offset];
  35 }
  36
  37 #define shmp(handle, ref)                                               \
  38         ({                                                              \
  39                 __typeof__((ref)._type) ____ptr_ret;                    \
  40                 ____ptr_ret = (__typeof__(____ptr_ret)) _shmp((handle)->table, &(ref)._ref);    \
  41                 ____ptr_ret;                                            \
  42         })
  43
  44 static inline
  45 void _set_shmp(struct shm_ref *ref, struct shm_ref src)
  46 {
  47         *ref = src;
  48 }
  49
  50 #define set_shmp(ref, src)      _set_shmp(&(ref)._ref, src)
  51
  52 struct shm_object_table *shm_object_table_create(size_t max_nb_obj);
  53 void shm_object_table_destroy(struct shm_object_table *table);
  54 struct shm_object *shm_object_table_append(struct shm_object_table *table,
  55                                            size_t memory_map_size);
  56
  57 /*
  58  * zalloc_shm - allocate memory within a shm object.
  59  *
  60  * Shared memory is already zeroed by shmget.
  61  * *NOT* multithread-safe (should be protected by mutex).
  62  * Returns a -1, -1 tuple on error.
  63  */
  64 struct shm_ref zalloc_shm(struct shm_object *obj, size_t len);
  65 void align_shm(struct shm_object *obj, size_t align);
  66
  67 static inline
  68 int shm_get_wakeup_fd(struct shm_handle *handle, struct shm_ref *ref)
  69 {
  70         struct shm_object_table *table = handle->table;
  71         struct shm_object *obj;
  72         size_t index;
  73
  74         index = (size_t) ref->index;
  75         if (unlikely(index >= table->allocated_len))
  76                 return -EPERM;
  77         obj = &table->objects[index];
  78         return obj->wait_fd[1];
  79
  80 }
  81
  82 static inline
  83 int shm_get_wait_fd(struct shm_handle *handle, struct shm_ref *ref)
  84 {
  85         struct shm_object_table *table = handle->table;
  86         struct shm_object *obj;
  87         size_t index;
  88
  89         index = (size_t) ref->index;
  90         if (unlikely(index >= table->allocated_len))
  91                 return -EPERM;
  92         obj = &table->objects[index];
  93         return obj->wait_fd[0];
  94 }
  95
  96 #endif /* _LIBRINGBUFFER_SHM_H */